The prototype aircraft, registered as PH-AFL and named 'Leeuwerik', completed its maiden flight on 5 December 1930. The first flight for KLM was on 5 March 1931. The official schedule started on 1 October the same year with PH-AFV 'Valk' that reached Batavia in about 81 hours flying time during ten days.

On most flights there were four to six comfortable seats available for sleeping on.

Following delivery of the full complement of eight F.XIIs, KLM operated its Indies route exclusively with the type.

The final F.VIIb-3m's were removed from the route and used for other purposes. Then, from August 1932, the F.XVIII supplemented the F.XII and later took over the route altogether.

This made the F.XIIs available for operation on scheduled European flights.

On the afternoon of 6 April 1935, PH-AFL crashed in a heavy snowstorm near Brilon, between Leipzig and Essen on the Prague-Rotterdam route. The F.XII flew into a mountain slope in conditions of blinding snow, thunder and unusual darkness. According to a German investigation report, visibility at the time of the crash was less than 250 ft.

The machine was totally burnt out. Two passengers and five crew members were killed, including Captain Pier Soer well known for his Christmas flight in a Fokker F.XVIII called 'Pelikaan', in 1933.

KLM also used the F.XII for charter flights. PH-AID 'Duif' was leased to the Irish Iona National Airways who wanted to start a mail and passenger service between Dublin and Berlin. To this end, KLM Captain Scholte with 13 passengers plus a large quantity of mail, took-off from Baldonnel near Dublin at 7.30 on the morning of 24 October 1932 and flew to Croydon.

The Duif then flew on via Waalhaven to Berlin where it arrived at 4.30 in the afternoon. This turned out to be the only flight as the Irish government was not interested in an air link between Dublin and European capital cities. In December 1933, four French scientists chartered PH-AM 'Havik' for a study tour of the Netherlands Indies. Flying out of Le Bourget airport, Paris, the aircraft was also captained by Scholte. By April, the Havik was back at Schiphol after a journey of more than 18,000 miles.

The machine was the last KLM F.XII to fly to the Indies. The Havik landed at Schiphol on 13 June 1935, marking the end of an era for the F.XII on this route.

Fokker F. XII

A loyal Indies aircraft

The F.XII was designed following a request from KLM for a three-engined commercial airliner with a capacity between that of the Fokker F.VIIb-3m and the Fokker F.IX.

It had also to have the same good performance and flying characteristics. Fokker built into the F.XII the experience it had gained from the Fokker F.VII, the Fokker F.VIII and the Fokker F.IX. The company's basic method of construction - a wooden wing and a tubular steel fuselage - was retained.

The F.XII wing had the same aspect ratio as that of the F.VIII. Power was provided by the engine locations were similar to those of earlier three-engined Fokkers: one engine in the nose and the other two under the wing. Initially the power units were uncowled, but later Townend rings were fitted.

The F.XII had protective cowls around its undercarriage wheels, but in practice these proved to be not very satisfactory. On rough terrain they were liable to collect large quantities of mud inside them.

The aircraft featured an enclosed cockpit for a two-man crew, and the cabin could seat 16 passengers. However, the machines which KLM put into service on its European routes in the main had 14 seats.

Crilly airways

When from 1935 onwards the Douglas DC-2 came into service with KLM, the airline sold four of its F.XIIs to Crilly Airways. This English operator wanted to open a service from London to Lisbon, with a possible later extension to Gibraltar and West Africa. After Crilly obtained permission from the British and Portuguese governments, one of the F.XIIs opened the service on 1 February 1936. However the project came to an end when the Spanish government refused Crilly permission to overfly its territory.

British Airways then took over the aircraft and founded a sister company, British Airways Iberia Ltd. with Leo Crilly as managing director.

But not even this company was able to keep going and it went bankrupt.

For the F.XIIs a new, at first unnamed buyer took them over. It was apparent however, to those in the know, that the aircraft were destined for the Spanish Nationalists and the Spanish Civil War. English pilots were to fly the aircraft via France to Burgos in Spain. Arriving at Bordeaux on 28 July 1936 they were arrested by the French Aviation Ministry on the strength of a non-intervention treaty regarding the Spanish Civil War. Following intervention by the the British government, the aircraft were returned to London Gatwick. At this point the internationally-known Polish arms dealer Stephan Czarniecki bought the F.XIIs supposedly to use them to open an airline in Poland.

One of the four Polish pilots who came to collect the aircraft confessed after an evening's drinking that he and his colleagues were fighter pilots,

not commercial pilots. It was no surprise therefore that, after departure from Gatwick, the aircraft set off not in the direction of Poland but of France, en route to Spain.

Because of bad weather above the Pyrenees Mountains, only one aircraft succeeded in landing on Spanish soil. Two aircraft crashed as a result of emergency landings, and the fourth flew back to Bordeaux where it was impounded.

Shortly after, to everyone's surprise, the French authorities released the aircraft and allowed it to depart for Spain. So ultimately two of the F.XIIs entered service on the Nationalist side in the Spanish Civil War.

The Nationalists rebuilt the aircraft as bombers, and later one was shot down on 16 December 1936 and the other survived the war but was demolished shortly after. The opposition in the Civil War, the Republicans, also had an F.XII at their disposal.

KLM had sold an F.XII to a French company, Air Tropique, which in fact existed only on paper. This 'company' routed the Fokker machine through to Spain where the Republicans rebuilt it also as a bomber. It is not known what became of this aircraft. Of KLM's remaining F.XIIs, two went to British Airways in October 1936 who put them into service on night mail flights to Cologne and Hanover.

One of the machines flew into a mountain on 19 November 1936, and the other was later acquired by British Overseas Airways in 1938. It was finally broken up in 1940.

KNILM

Following KLM, two F.XIIs were ordered by KNILM, KLM sister company in the Dutch East Indies.

These performed entirely satisfactorily and remained in service until the Japanese invasion. On 19 February 1942, one of the F.XIIs was hit by debris from an exploding bomber during a Japanese attack on Semlak airport in Java.

The other aircraft fell into Japanese hands after the surrender of Andir airport near Bandoeng. Initially KNILM had planned to operate four F.XIIs as shown by the registration numbers that had been reserved for them.

It is not known why these aircraft did not go ahead. The eleventh and final F.XII built by Fokker went to the Swedish airline Aktie Bolaget Aerotransport (ABA) in February 1932.

This purchase was made on the basis of KLM's favorable results with the type.

Together with ABA, KLM operated the 'Scandinavian Air Express', flying London-Paris-Amsterdam-Copenhagen, with connecting flights to Stockholm, Tallinn in Estonia, and Leningrad. ABA put the aircraft into service on the route Malmbö-Amsterdam-Berlin-Copenhagen-Göteborg. The F.XII's engines were fitted with Townend rings and the wheels with streamlined 'spats'.

The cabin was very comfortably equipped with armchairs designed by ABA. On the ceiling was a map of the countries over which ABA flew with the Fokker machines. Passengers were very complimentary about the Dutch aircraft. They praised the comfort, lack of draughts and the reduced noise in the cabin, features that were rarely available on other aircraft of the time. ABA was also very pleased with the technical reliability of the aircraft. It was not until 1946 that ABA sold its FXII to Svensk Flygtjansk, who flew joy rides with it at Bromma airport near Stockholm.

There the F.XII was lost in a hangar fire on 9 April 1947.

DDL

The final customer for the F.XII was the Danish Det Danske Luftfartselskab (DDL) who also placed their order following the favorable experience of KLM. The aircraft was built under license by Danske Orlogsvaerftet in Copenhagen who completed its construction within only three months of receiving the contract. Delivery took place on 11 May 1933.

The machine was equipped with three 465 hp Bristol Jupiter engines, and was given the name 'Merkur'. DDL used the F.XII in a configuration seating 16 passengers on their Copenhagen-Berlin route.

The good results persuaded the management to order a second aircraft that was delivered on 13 May 1935. Because of changes introduced on this machine, its designation was modified to F.XIIM.

This version was 12 mph faster than the standard F.XII. Even during the war, DDL flew both machines from Copenhagen and Malmö to Hamburg, Berlin, Munich and Vienna. Both aircraft continued through the war and the last of them was demolished following a hangar fire in 1947.